# Best way to treat rechargeable batteries

Discussion in 'Architecture & Engineering' started by Fraggle Rocker, Aug 15, 2011.

1. ### billvonValued Senior Member

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How to care for secondary batteries:

NiCd - keep them cool, cycle them shallowly, occasionally deep discharge them and recharge them.

NiMH - keep them cool, cycle them shallowly. No need for deep cycles (it just wears them out faster.)

Lead-acid - keep them cool, keep them fully charged as much as possible, cycle them shallowly. Do not allow them to discharge completely during storage.

Lithium ion - keep them cool, keep them at 30-50% charge as much as possible. Shallow cycles. Do not store fully charged and do not store completely discharged.

3. ### Billy TValued Senior Member

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On first three I agree but want to note there are two types of Lead-acid batteries on the market: Those used to start cars need high amperage discharge capacity for about a second and don't make much internal heat during that second. I.e. they need huge surface electrode areas to get that high current. If you take most of the energy out during one discharge, the heating will warp their thin electrode plates - destroying the battery. Even just leaving the car head lights without motor running is on until the battery is drained few times will greatly reduce its life (but most have plates thick enough not to buckle and touch, the first time you forget to turn the lights off).

The other 12V Lead-acid type is designed with much thicker electrode plates but only about 10% as many of them. - You can not get the "cranking current" needed to start your car from so little electrode surface area, but you can run a small electric motor for several hours on it to deep discharges state with little damage to the battery.

I used one of this type to troll (for fish and women) on the drinking water reservoir just North of Baltimore and close to Gaucher College, which was women only then. One of them was usually with me in the boat. Gasoline outboard motors were not allowed as the public does not like the taste of even tiny gasoline contamination in their drinking water.

My laptop's Li-ion battery is now more than 5 years old and "like new" in capacity (I think- I have not tested with timing to full discharge and no use of disk for many months). It is out of the computer all day and only provides power during computer shut down, OR during next morning turn on. I.e. at end of day I turn off charger, go to bed not waiting for logical shut down to complete. At start of day I turn charger back on. Often so little energy has been taken from the battery (by shut down operations and over night self discharge) that the battery charge state light is green almost immediately at turn on, but if yellow, the battery will fully recharge and then be removed from computer as soon as I notice the light has turned green.

I don't trust the circuits to put zero current into a fully charged battery - so mine is out of the computer except for a few minutes each day. - Heat accelerates diffusion aging and temperature cycling makes small mechanical damage. I do not believe slow self discharge from the fully charged state WHILE NOT CONNECTED TO ANY CIRCUIT damages a Li-ion battery, but if connected to a typical charger all day, I bet it gets a lot of shallow charge cycling and if in a turned on computer, it get quite warm.

Last edited by a moderator: Aug 21, 2011

5. ### leopoldValued Senior Member

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i have never seen the term "solid state" in reference to batteries in any literature until i seen it here when fraggle used it.
the types of circuits you describe are called "passive" not "solid state".

In order for a circuit to be properly called electronic, it must contain at least one active device. Components incapable of controlling current by means of another electrical signal are called passive devices. Resistors, capacitors, inductors, transformers, and even diodes are all considered passive devices.

Last edited: Aug 21, 2011

7. ### quadraphonicsBloodthirsty BarbarianValued Senior Member

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Yeah, I've read about those being used in the Netherlands (IIRC). Cool(est) thing there is that since the motors are in the wheels anyway, you can do much more with regenerative braking than in the usual hybrid cars. In an ideal design, there'd be no friction breaks at all, and essentially all braking energy would be recovered.

8. ### quadraphonicsBloodthirsty BarbarianValued Senior Member

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There is no such generation. Lots of things, can't be done virtually.

That much is true - but there are a lot of things that can't be done so well remotely. If we're talking about some semi-menial job, then maybe. But as soon as there's serious teamwork involved, or truly collaborative efforts (and most good jobs feature both of those elements), telecommuting doesn't work so great. This is already known by managers - it isn't like they wouldn't like to let everybody work from home (and have everyone be happy and save a ton on office space), but resist out of some kind of dated ideological crustiness. I work in a high-tech company where everyone does a lot of work from home (on top of being in the office pretty much full-time), and management has done pretty careful accounting of why they do, indeed, need you to be physically present most of the time.

Uh.... have you never encountered a salary job? Or a freelance job? How many hours I spend at my desk doesn't figure anywhere into my compensation. Frankly, I don't think any job that even involves sitting at a desk works that way any more (okay, maybe secretaries, but not much else). The sorts of jobs that pay by the hour, tend to involve shovels or flipping burgers - making it somewhat difficult to "look busy" without actually working.

Okay, this kind of bureaocratic position is one significant area in which I can see telecommuting paying off - and management resisting for reasons of ideological inertia. Also because all of those buildings (and parking lots) are expensive and add to tax overhead.

You still make grocery lists? There's an app for that (actually, more like 20,000 apps for that). You do have a smartphone, right?

.... ah. This is something of a liability for you to admit, in the middle of advocating paperless telecommuting. The whole thing about telecommuting and pervasive access is that it erodes the work-life balance. Having done a considerable amount of telecommuting, I found that one major downside is that just as you are never really "in the office," neither are you ever really "at home." And I've found that managers, even reasonable ones who are open to telecommuting, tend to - reasonably - expect a high level of reach-ability out of those who telecommute.

There is something to having a significant physical separation between your home and work lives. I'm no fan of big car commutes by any means, but neither do I particularly enjoy having work invade my home life.

Now, this is something that the "next generation" is definitely going to prove wrong in short order...

9. ### quadraphonicsBloodthirsty BarbarianValued Senior Member

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Vacuum tubes are active, electronic components.

And "passive" is not exclusive of "solid state." There are plenty of passive solid-state devices - your regular resistor, for example. There are also plenty of active devices which are not solid-state - vacuum tubes, again. "Solid-state" just means that the currents in question are moving around in materials in a solid phase - and not liquid, or gas, or vacuum, or plasma.

That's not quite right either. The difference between an electronic component, and a merely electrical component, is that the former's operation depends on an electron (i.e., particle) model of electricity. An electrical component only relies on electricity in the classical sense (i.e., without an electron particle aspect). Diodes are most certainly electronics, even if they are passive.

But we weren't talking about what can be called "electronic," but what can be called "solid state." And note, again, that a vacuum tube is a active device, an instance of electronics (under your own definition, as well as mine), and not solid-state.

And, yes, BTW I do have a PhD in EE.

10. ### OnlyMeValued Senior Member

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I really like the wheel motor and even some of the motor designs that operate similarly as a drive motor apart from the wheel itself. My trike has an electric hub that is in essence the same thing.

The dynamic or regenerative braking is nice but not really an efficient regeneration mechanism. Additionally when used as a full breaking system the motor has to shift at some point from a regen phase to an active motor operating against the direction of motion. It actually costs more in energy than conventional breaking systems.

In a larger platform like a locomotive, regenerative braking which in that case is referred to as dynamic braking is an essential component in breaking, but it does not provide any regen as these are mostly inline systems, with no battery to recharge. It may be that in a third rail type of system regen could supply power back to the external power system, I am not really sure in that case.

11. ### billvonValued Senior Member

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Actually with geared designs you can regen brake a lot more effectively, since most regen braking is torque limited, and magnet strength sets a hard upper limit on torque in ungeared motors. Hub motors are pretty cool, but the only two big advantages they have is that they're completely silent and they don't need driveshafts. In terms of everything else (efficiency, max power, weight, torque) they're somewhat limited.

You can come to an almost complete stop with regen, but you either need friction brakes or have to "go active" (i.e. drive the motor backwards) to eliminate brakes completely. But you can definitely get to 90%. In the Tesla, for example, the only time you have to touch the brake pedal is to come to a complete stop at a light.

12. ### billvonValued Senior Member

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I agree there. However, deep cycle batteries still last longest when you keep them cool, and fully charged as long as possible.

Also agreed, provided it does not self-discharge down below about 2.5 volts per cell. Unfortunately all li-ion batteries are always connected to a circuit, since they require full time electronic protection circuits to protect against overloads. Fortunately designers have gotten very good at designing these to take minimal power, so you can expect a properly stored 50% charged li-ion cell to last years before it drops to a voltage that will damage it.

13. ### KilljoyKlownWhateverValued Senior Member

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I think for the money I'd go for a Karma over the Tesla at this time.

Vehicle Highlights

The 2011 Fisker Karma is a new gas/electric hybrid luxury car. Originally slated for introduction during the 2010 model year, this 4-door, rear-wheel-drive sedan is built in Finland and distributed by U.S.-based Fisker Automotive, Inc. It pairs a battery-powered electric motor with a turbocharged 2.0-liter 4-cylinder engine for 403 horsepower total. Unlike most hybrids, Karma uses plug-in technology the company calls Q DRIVE. It can run up to 50 miles solely on electric power. After that, the gasoline engine turns on a generator, which charges the car's lithium-ion battery pack to provide power to the electric motor. Since the electric motors drive the wheels directly, no transmission is needed. The driver can select between two driving modes. Stealth Drive is designed for maximum fuel economy. Sport Drive alters drivetrain behavior for maximum performance. An optional solar roof panel allows for additional battery-charging capability, and it's designed to keep the cabin cool on warm days. Available safety features include ABS, traction control, antiskid system, curtain-side airbags, and front-side airbags. Trim levels include EcoBase, EcoSport, and EcoChic. All use a touchscreen interface for climate and audio controls. EcoSport models have leather upholstery. EcoChic versions have fabric seats made from bamboo viscose. We have not yet tested the 2011 Fisker Karma.

14. ### leopoldValued Senior Member

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one or two paragraphs? a "whole" page?. created in 2009?
the only reference to a "battery" was in connection to fuel cells.
yes, i know.
resistors are not called "solid state" in the industry
vacuum tubes are the only non solid state active device i am aware of.
"solid state" in reference to electronics specifically refers to transistors and indirectly to integrated circuits.
once again no. transistors rely on both electrons and holes to conduct current.
the doping of transistor materials is specifically done to introduce these holes into the P and N types.
electrons are the conveyor of electricity, where are you getting this stuff?
i never stated a vacuum tube wasn't an active device nor did i say it was solid state.

edit:
i guess you can say it comes down to semantics.
the fact remains though, resistors although "solid state" are called passive devices.
semiconductor diodes are even more crazy, they can honestly be called "solid state" because of the similarities with the transistor, but alas they too are called passive devices.
even the phrase "solid state physics" is directly related to semiconducting materials.
these materials are to my knowledge only found in transistors, diodes, and integrated circuits.

Last edited: Aug 24, 2011
15. ### OnlyMeValued Senior Member

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3,905
Since we're talking money now, just what is the price tag?

16. ### KilljoyKlownWhateverValued Senior Member

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2012 Fisker Karma Base Price: $96,895 Tesla Roadster Base Price:$109,000

Not a big difference in price in that range.

But my consideration is that I like the Karma Hybrid over the all electric Tesla for a lot of reasons besides the cost.

17. ### Billy TValued Senior Member

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22,385
To leopold99

"Solid State" is sub division of physics. I studied it from Kittel's book with that name. One of the important concepts* of Solid State physics is the "Fermi level" which can be changed by "doping" - I.e. understanding this lead to the invention of SS diodes and transistors both of which come late in the history of solid state physics.

Sure they are now a large part of solid state physics' applications, but there is also a huge amount of knowledge about solid state that it totally unrelated to electronics of any type. For example, pure iron change between body centered cubic to face centered cubic crystal structure (a phase change, with associated latent heat, just like ice's 90cal/gr latent heat. Unlike ice melting, this is only a phase change but not a state change also as ice's solid to liquid is). These two different solid iron phases have different mechanical, thermal, electrical, magnetic properties as well as different specific heats.

Only your lack of education makes you think "solid state" refers only to electronic devices.

----------------
*Some of the others are why heat capacity of solids change with temperture as it does. Why magnets and super conductors are possible and what limits their max temperture. How index of refraction and reflection relate to the atomic properties. How diffusion works in crystals and what impurities can do to it. How "cold working" hardens many solids. How additives to iron can retard rusting. How thermal conduction works in non-metals and why some crystals, like diamond, are better conductors than copper, etc. for several dozen other aspect of solid state physics than have nothing to do with electronics and some precede SS electronic by hundreds of years!

BTW, there are even solid state "batteries" that never need to be recharged - just keep their ends at different temperatures, which are well understood by solid state physics. Some have gone into space on journies going far from the sun.

Last edited by a moderator: Aug 25, 2011
18. ### quadraphonicsBloodthirsty BarbarianValued Senior Member

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This makes sense, but my understanding is that what limits the regen braking (at least, in consumer hybrid/electrical cars) is the cost/weight associated with adding high-power systems to the wheels. I.e., they limit the amount of regeneration to only a small fraction of the braking energy in order to keep the regen brakes added to the wheels cheap and light-weight. So supposedly only something like 10% of the energy you could extract actually gets used in practice - but a hub motor system doesn't have this constraint, because you've already put a high-power motor system right into the wheel anyway. So even with the limits you mention, it's supposed to vastly outperform existing approaches.

19. ### quadraphonicsBloodthirsty BarbarianValued Senior Member

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And... ?

Only to the extent that it's rarely required to specify what phase of matter a resistor is in. The exception being certain high-powered systems that use liquid resistors.

And... ? That's an entire class of active devices that are not solid state, and which existed for decades before solid state devices were ever invented. This definitively establishes that "solid state" does not mean "active device," nor vice-versa.

It is most heavily used with that connotation - exactly to differentiate from vacuum tubes - but the specific definition of "solid state" is just that: the currents are in material that is in the solid state.

You miss the point entirely - you need a particle theory of electricity (i.e., "electrons") to work out the operation of such a device (regardless of whether the currents are mediated primarily by holes or not). That's why it's "electronics." You can't explain their operation with older ideas of electricity - simple "current" and "charge" absent an explicit particle model of the materials and their electromagnetic properties.

But nobody had ever heard of an electron until many decades after the principles of electric circuits and devices was developed. Ohm's Law, Faraday's Law, classical E&M, etc. - all the stuff that describes how resistors, capacitors, inductors and transformers work, predates the discovery of the electron by like 50 years. Faraday and Ohm were long dead before the word "electron" was ever coined.

Hence, electrical devices - as distinguished from electronics - do not rely on the electron model of electricity. They only need the macroscopic concepts of "charge," "current," "voltage," etc. The fact that there are individual, indivisible units of charge, doesn't come up in electrical devices. But it is crucial to electronic devices - that's where the names come from.

Well yeah...

Which demonstrates exactly my point that "solid state" and "active" are separate things. There are passive, solid-state devices, and active, non-solid-state devices. There are passive, non-solid-state devices, and active, solid-state devices.

Which, again, demonstrates that "solid state" and "passive" are not exclusive of one another.

Solid-state physics is just that: the physics of solid materials. It has as much to do with the thermal properties of insulators, or the optical properties of conductors, as it does with the electrical properties of semiconductors.

A semiconductor is simply any material with conductance greater than an insulator, but less than a conductor. A lump of silicon, is a semiconductor. There are also liquid semiconductors - so that is again not a "solid state" only thing. Semidconductors exist all over the place, although it's true that about the only interesting thing about them is their applications in (mostly, solid-state) electronics.

And you're also forgetting photovoltaic cells.

20. ### elteValued Senior Member

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1,256
I'm thinking besides vacuum tubes, a couple other active devices that aren't solid state include relays, and vibrators like used in early car radios. I can't forget to mention the magnetic amplifier, a specially used transformer that can be caused to amplify by controlling its saturation by means of one of its windings. I understand the Germans used them a lot during WWII.

21. ### KilljoyKlownWhateverValued Senior Member

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I've never done any of those things you mentioned, but I've known some people that would do that stuff without even giving it a second thought, especially with someone else's stuff. Glad I don't know them anymore.

22. ### auserRegistered Senior Member

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6
That is a respectable life time for a li-ion battery, which most portable devices use these days. The li-ion batteries degrade over time even when not used. I believe some will degrade to 80% in a year without ever being used if left stored at a full charge. Also, they have a limited amount of cycles, ~500-1000, so if you use it everyday for two years that is over 700 cycles.

23. ### KilljoyKlownWhateverValued Senior Member

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Hi auser, welcome to the forum. My experience with those batteries agrees with what you just said. I have to recharge my phone every 3 days whether I use it or not. Also, my experience with laptops, is they start having battery problems after about a year when they are used daily. I know a lot of people that use their laptops in bed. If you set a laptop on a bed they get very hot because of the lack of air circulation under it. I'm not sure but I think the heat can't be good for the batteries and probably helps wear them out faster.